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The fourth-generation Jeep Grand Cherokee was introduced in 2011. This model is also known as Jeep WK2.

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Why is my car lossing power and feeling sluggish

My car was recently acting up with feeling sluggish from a dead stop and having issues accelerating. We thought it was the Throttle Body, which we replaced and no change. Then my car was also throwing codes saying it was the Crankshaft Sensor and multiple cylinder misfire. So my husband changed out the sensor and then changed all 16 spark plugs where 14 of them were fouled out. After he was done, went to test drive and nothing has changed! What else can it be?! Feeling frustrated cause its also resulting in me only getting like 100 miles per a tank, I have literally filled my car up 3 times in the past 3 days.

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Hey Samantha.

The specific conditions found with the spark plugs (those which were fouled) are useful in these diagnostics. Were they burned up, gas fouled, or oil fouled, or …? With all those plugs being fouled it’s hard to understand how this engine could actually start or run at all.

Ask your husband to check to see that you’re getting spark at the cylinders. If he finds a no spark condition, he might suspect an issue with the ignition control module, or a bad plug wire, or bad distributor cap, etc.

If all cylinders are getting spark, may want to look at a possible failure with ignition coils for each cylinder. It’s also possible that the ignition timing is the culprit.

Note that the wiring, connectors and actual connections for these parts can be the cause of a failure, too, due to corrosion, wear and/or physical damage, etc.. Also, the same would apply to the sensors he’s already replaced.

Can’t offer more specific information unless you provide the specific on your vehicle, but maybe this might at least aide in pointing you in a helpful direction.

Update (07/19/2019)

@Samantha Roach Gas fouled plugs tell you that for some reason that cylinder is not firing/igniting the mixture. That means you're running on fewer cylinders and thereby making less power. It also means that fuel is being spent without benefiting the engine, it’s power, your mileage or your pocketbook. Further, this raw fuel then must be dealt with in the exhaust system and probably saturating things in the catalytic converter.

A improper spark plug gap may prevent the spark from arcing, not enough air intake can compromise the fuel mixture so that it doesn't ignite, and an issue with an ignition coil might prevent it from sending the spark at all, or the timing being off might have the spark occurring at the wrong time. In that there’s so many cylinders failing all at once, it seems that generation or distribution of spark, or the timing being off, is more plausible (look for and follow the spark).

The Throttle Position Sensor signals the computer to adjust the fuel settings at the injectors, to maintain the proper fuel/air mixture throughout acceleration and deceleration. It’s actually monitoring how much air is being demanded based on the position of the throttle, which tells the computer how to adjust the fuel portion. A clogged or restricted or obstructed air intake might not be allowing as much air in as the throttle position is calling for, but the computer wouldn’t know that, and increasing the fuel portion would then make the mixture too rich to ignite. This could occur as result of something as simple as a clogged up air induction filter that needs replacing.

When replacing the TPS, know that it’s position is a factor. Use a multi-meter to find the point where the highest resistance/lowest voltage (= to ~0.5 DC volts) is displayed, and secure the TPS in that position. Since this was already replaced, ask your husband if this was taken into account. If not, he may need to reset the TPS’s position.

Also, be aware that the throttle body itself could be contributing to the problem simply due to needing cleaning.

Hope something in this might help. Please keep us posted.

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5 Comments:

I believe it was gas fouled, he was not seeing any issues anywhere else in regards to wiring or anything. But if those issues do lie, wouldn't you get a code in regards to those items if the check engine light was on?

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@fixnpop59 Tony. you really give quality answers and your participation is really appreciated, at least by me. If you get an opportunity please tell us more about yourself on your profile. The regular contributors here are a great group of guys. Opps, there's also one lady in the group @ladytech , almost forgot @salmonjapan Augustine (but she doesn't talk much about herself.

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@mayer I appreciate that, mayer. Especially coming from you, given the knowledge and experience you obviously possess. I've taken notice of a few others, also, those you mentioned included. Didn't realize if or how contributors could interact on this site. Actually, I'm likely missing a number of things about it, and it's unclear just how everything works.

As for the brevity of my profile, I guess I could try to expand a bit,.. and will.

Thanks again.

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@fixnpop59 Tony, check out the Meta site where we interact with the iFixit Staff:

https://meta.ifixit.com/Answers

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@mayer many thanks, sir. will do.

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